Composition of cast-iron.



UNITED STATES COMPOSITION OF CAST- IRON.

Specification of Letters Patent.

Patented Feb. 2'7, 1917.

No Drawing. Original application filed August 13, 1913, Serial No. 785,492. Divided and this application filed July 31., 1914.

To all whom it may concern:

Be it known that I, JOSEPH E. JOHNSON, Jr., a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Composition of Cast-Iron, of which the following is a specification.

This invention relates to an improved composition of cast iron, more particularly cast iron produced by the coke process, the object of the invention being to give the desirable qualities of, strength, density of grain and chilling properties, to the more inexpensive cast irons, such as are produced by the coke process of smelting, and to other irons which do not possess such qualities, these qualities being now exclusively possessed by the more expensive high grade cast irons, such as are produced by the charcoal process of smelting.

By experiments and analyses, I have found that, contrary to the universal belief, the

desirable qualities possessed by these high grade irons, are due to the presence of oxygen therein, which does not exist in the cheaper coke irons in adequate quantities. The qualities mentionedare'possessed more by charcoal iron than by coke "iron, and more by cold blast charcoal iron than by hot blast charcoal iron. The temperature at which these irons are made, is lower in the order given, coke iron being made at the highest temperature, hot blast charcoal iron at the next highest temperature, and cold blast charcoal iron at the lowest temperature. The aifinity of carbon and silicon for oxygen, increases with temperature, hence the oxygen which can and does exist in the cold blast charcoal iron, does so to a less extent in hot blast charcoal iron, and to little or no extent in coke iron. In an application for patent filed by me on the 13th day of August, 1913, Serial No. 785,492, I have described and claimed a method of treating cast iron, by which, a sufiicient amount of oxygen is incorporated in the. iron to give it the desirable qualities above mentioned.

The present application is a division of said prior application and is based on. the improved cast iron resulting from said process, and the invention consists of a cast iron, consisting o coke iron, containing the usual main characteristic elements of cast iron,

Serial No. 854,265.

such as carbon and silicon, together with oxygen. I

I prefer, in incorporating the oxygen in the iron in producing my improved cast iron, to proceed in the manner set forth in said original application above mentioned, but it will be understood that the present invention is not restricted in its scope to any particular method of procedure, ap-

paratus, or means for effecting the incorporation of the oxygen, but comprehends and covers the improved cast iron composi tion, without regard to the manner of producing the same, said cast iron composition consisting of coke'iron containing the usual main characteristic elements of cast iron, such as silicon, carbon, and in addition such quantity of oxygen as will give to the product, the desirable qualities above mentioned with respect to strength, density of grain, and chilling properties.

In producing my improved composition of cast iron, one method, as set forth in said original application, is to oxidize by any suitable oxidizing agent, either solid, liquid or gaseous, a bath of ordinary cast iron outside the blast furnace, at a'considerably reduced temperature, the purpose being to prevent the elimination or substantial reduction of the carbon, while at the same time, burning out the. silicon to a point Where itwill no longer combine with the oxygen. After this point is reached, the addition of oxygen is continued, with the result that the bath being no longer protected by the silicon against the absorption of oxygen, the latter will be taken up and retained by the bath. Silicon is then added to the bath to give the vfinal product the proper proportion of this desirable characteristic element. The incorporation of the silicon may be conveniently efiected by adding a quantity of molten metal from the blast furnace, and containing the usual or normal amount of silicon, to a bath of the same metal which has had the silicon removed or reduced, and the oxygen in corporated, as above described, the result of which will be a mixture containing carbon and silicon, and in addition, oxygen. In incorporating the silicon, considerably more is customarily added than would be necessary to remove all the oxygen present, but as the reaction between the two does not proceed to completion, because of the low temperature, therefore the desired amount of oxygen remains, as Well as silicon.

The product of this procedure will be a cast iron consisting of coke iron containing the usual main characteristic elements of cast iron, such as silicon and carbon, and containing in addition, a proper proportion of oxygen. A coke iron of this composition possesses all of the desirable qualities characteristic of high grade expensive charcoal iron, these characteristics being due to the presence of the oxygen in the coke iron. The improved product is therefore capable of economic production, While possessing the desirable qualities with regard to strength, density of grain and chilling properties, which have never heretofore been secured except in the more expensive and high grade irons.

The final product constituting my invention, possesses qualities totally different from the original metal from which it is produced, even though its silicon and carbon content may be virtually identical With those of the original metal. These changes in quality are briefly: a great reduction in the size of the grain; a great increase in strength; and an increase of the depth to Which the metal will chill or become White When cast against a chilling object, these changes being due to the fact that the metal contains in addition to the metalloids which constitute it cast iron, oxygen, which so influences the other elements present as to give the final product these desirable qualities.

The composition of the final product may vary within certain limits With respect to the proportion of the constituent elements, but should in order to best realize the advantages of my invention, be substantially as follows:

.Carbon from 3.25 to 3.75 per cent.

Silicon from .75 to 1. per cent. Oxygen from .04 to .07 per cent.

I have not made special reference in the foregoing description to other elements appearing characteristically in cast iron, such as phosphorus, sulfur and manganese, as these elements occur in all cast iron, in proportions which vary Within limits Well known to the metallurgist, and their pres ence in the iron does not exert any particular influence, in the incorporation of the oxygen, except perhaps manganese, which for the best results should be kept at a low percentage, say from .50 to .75 per cent.

It is to be noted that in my improved composition of coke iron, the oxygen is present in known, definite and controlled quantity, as also are the other ingredients, their proportions being predeterminately and definitely selected to give the product the desired qualities of strength, density of grain and chilling properties. This gives the final product uniformity of composition, and enables the user to determine in advance just What qualities Will be possessed by the castings made therefrom.

Having thus described my invention, what carbon and oxygen in controlled and proper proportions to give to said composition the qualities of strength, density of grain, and chilling properties.

5. The improved composition of cast iron, consisting of coke iron, containing carbon, silicon and oxygen in controlled quantities and in substantially the proportions mentioned.

6. The improved composition of cast iron, consisting of coke iron, containing in controlled quantities silicon from .75 to 1 per cent; carbon from 3.25 to 3.75 per cent; and oxygen from .04 to .07 per cent.

In testimony whereof I have affixed my signature in presence of tWo Witnesses.

JOSEPH E. JOHNSON, JR. Witnesses:

GEO. W. HAULENBEEK, ROWLAND Gosnnnn. 

